An epidemiologic study of Helicobacter pylori infection in three areas with high, moderate or low incidences of gastric carcinoma

Table 1 Helicobacter pylori infection rates of subjects from areas with low, moderate, and high incidence rates of gastric cancer

Age (yr)	Low (Conghua County)		Moderate (Huaiyuan County)		High (Changle County)
	n	Positive rate (%)	n	Positive rate (%)	n	Positive rate (%)
1-4	13	15.4	14	35.7	14	50.0
5-9	43	30.2	17	41.2	42	54.8
10-19	32	37.5	23	43.5	32	53.1
20-29	27	33.3	66	63.6	44	72.7
30-39	30	33.3	34	64.7	40	67.5
40-49	23	43.5	28	53.6	19	47.4
50 +	29	41.4	31	58.7	38	55.3
Total	197	34.5	213	55.9a	229	59.4a

χ² = 25.029,

^aP < 0.05, compared with the area of low incidence rate (Conghua County)